Stability Balls in the Classroom

Stability Balls - Have any of you used them in the classroom?  They are supposed to be great for ADHD students and kinesthetic learners, but from what I've read, they improve overall attention and behavior for almost every student.  I'm just curious to hear first-hand reviews.  One teacher at my school has enough stability balls for half of her class.  (A relative is doing research and funded the balls for her.)  I know they're expensive.  If I decide to go this route, I will have to write a Donors Choose to try to get it funded.  Does anyone have suggestions for grants other than Donors Choose?

Oh!  I haven't mentioned, my Donors Choose project for the Chromebooks was fully funded within one week of being posted!  How exciting!!  I won't receive the Chromebooks until school starts in August, but it's going to be a great asset!